Convert spellcheck to a buildflag header.

chrome/browser/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
 import("//components/os_crypt/features.gni")
+import("//components/spellcheck/spellcheck_build_features.gni")
 import("//extensions/features/features.gni")
 import("//media/media_options.gni")
 import("//net/features.gni")
 import("//ppapi/features/features.gni")
 import("//printing/features/features.gni")
 import("//third_party/protobuf/proto_library.gni")
 
 # //build/config/android/rules.gni imports //tools/grit/grit_rule.gni, which
 # produces a conflict for the "grit" template so we have to only include one.
 if (is_android) {
@@ skipping 1352 matching lines @@
     "//components/resources",
     "//components/safe_browsing_db",
     "//components/safe_json",
     "//components/search",
     "//components/search_engines",
     "//components/search_provider_logos",
     "//components/security_interstitials/core",
     "//components/security_state",
     "//components/sessions",
     "//components/signin/core/browser",
+    "//components/spellcheck:build_features",
     "//components/ssl_config",
     "//components/ssl_errors",
     "//components/startup_metric_utils/browser:host",
     "//components/startup_metric_utils/browser:lib",
     "//components/storage_monitor",
     "//components/strings",
     "//components/subresource_filter/content/browser",
     "//components/subresource_filter/core/browser",
     "//components/suggestions",
     "//components/supervised_user_error_page",
@@ skipping 3008 matching lines @@
   # linking all of the test support.
   static_library("pepper_cdm_test_constants") {
     testonly = true
     visibility = [ "//chrome/*" ]
     sources = [
       "media/pepper_cdm_test_constants.cc",
       "media/pepper_cdm_test_constants.h",
     ]
   }
 }